Type-I superconductivity in KBi<sub>2</sub>single crystals

Sun, Shanshan; Liu, Kai; Lei, Hechang

doi:10.1088/0953-8984/28/8/085701

Cited by 35 publications

(51 citation statements)

References 26 publications

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“…Although there is a diamagnetic transition in the magnetic susceptibility χ(T ) curves at T c,onset ∼ 2.8 K when H = 10 Oe with zero-field-cooling (ZFC) and field-cooling (FC) modes and the transition temperature is close to that corresponding to the drop in the ρ xx (T ) curve, the superconducting volume fractions are very small (∼ 1 and 2 % at 1.8 K for ZFC and FC χ(T ) curves). Because the T c is close to that of KBi 2 (T c = 3.57 K), 45 this superconducting phase could originate from the tiny of KBi 2 . But it has to be mentioned that we measured at least ten samples that are carefully cleaved, cut and scratched, and all of samples exhibit superconducting transition with similar T c .…”

Section: 50mentioning

confidence: 90%

Narrow-gap semiconducting properties of KMgBi with multiband feature

2017

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KMgBi single crystals are grown by using the Bi flux successfully. KMgBi shows semiconducting behavior with a metal-semiconductor transition at high temperature region and a resistivity plateau at low temperature region, suggesting KMgBi could be a topological insulator with a very small band gap. Moreover, KMgBi exhibits multiband feature with strong temperature dependence of carrier concentrations and mobilities.

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Section: 50mentioning

confidence: 90%

Narrow-gap semiconducting properties of KMgBi with multiband feature

2017

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“…This effect is observed for mixed state of type-I superconductors or in type-II superconductors with close H c1 and H c2 values. considered to be type-I superconductors and, generally, is associated with sample shape effects, domain or grain walls etc [29,[31][32][33][34]. Temperature dependences of the specific heat in various magnetic fields are shown on Fig.…”

Section: Resistivity Specific Heat and Magnetic Susceptibilitymentioning

confidence: 99%

Electronic band structure and superconducting properties of SnAs

et al. 2019

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We report comprehensive study of physical properties of the binary superconductor compound SnAs. The electronic band structure of SnAs was investigated using both angle-resolved photoemission spectroscopy (ARPES) in a wide binding energy range and density functional theory (DFT) within generalized gradient approximation (GGA). The DFT/GGA calculations were done including spin-orbit coupling for both bulk and (111) slab crystal structures. Comparison of the DFT/GGA band dispersions with ARPES data shows that (111) slab much better describes ARPES data than just bulk bands. Superconducting properties of SnAs were studied experimentally by specific heat, magnetic susceptibility, magnetotransport measurements and Andreev reflection spectroscopy. Temperature dependences of the superconducting gap and of the specific heat were found to be well consistent with those expected for the single band BCS superconductors with an isotropic s-wave order parameter. Despite spin-orbit coupling is present in SnAs, our data shows no signatures of a potential unconventional superconductivity, and the characteristic BCS ratio 2∆/Tc = 3.48 − 3.73 is very close to the BCS value in the weak coupling limit.

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“…There are several bismuthalkaline and alkaline-earth metal intermetallic superconductors known, including LiBi [6], NaBi [7], KBi 2 [8], RbBi 2 , CsBi 2 [9], Ca 11 Bi 10-x [10], SrBi 3 [11,12], BaBi 3 [13], and Ba 2 Bi 3 [14]. Recently, intermetallic phases in the Ca-Bi chemical system were examined using theoretical calculations, and three potential superconductors were proposed: CaBi 3 , CaBi, and Ca 3 Bi [15].…”

Section: Introductionmentioning

confidence: 99%

Superconductivity in CaBi₂

Winiarski

Wiendlocha

Gołąb

et al. 2016

Phys. Chem. Chem. Phys.

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and 124 Oe. Results of electronic structure calculations are reported and charge densities, electronic bands, densities of states and Fermi surfaces are discussed, focusing on the effects of spin-orbit coupling and electronic property anisotropy. We find a mixed quasi-2D + 3D character in the electronic structure, which reflects the layered crystal structure of the material. Keywords: Type-I superconductivity, 2 I IntroductionMuch effort has recently been devoted to Bi-based candidates for topological insulators [1,2,3]. The presence of the heavy element bismuth provides the strong spin-orbit coupling that is essential for formation of the topologically-nontrivial band structure of these materials. To the best of our knowledge, no report on the physical properties of CaBi 2 has been previously published. CaBi 2 crystallizes in an orthorhombic lattice in non-symmorphic space group Cmcm (no. 63) [19], and is isostructural with ZrSi 2 [21,22]. In order to study the electronic properties of CaBi 2 , we employed a self-flux-based single crystal growth method [32], and the physical properties of the resulting crystals were analyzed. The electronic structure of the system was next calculated, using density functional theory methods. Electronic bands, densities of states, Fermi surfaces and charge densities are described here in addition to the electronic properties of the material; the analysis focuses on spin-orbit coupling effects and the anisotropy of the electronic states. II Materials and MethodsTo grow the CaBi 2 crystals, calcium granules (Alfa Aesar, 99.5%) and bismuth pieces (Alfa Aesar, 99.99%) in a 3:17 molar ratio (15 at% of Ca) were put in a carbon-coated quartz tube inside an Ar-filled glovebox. A plug of quartz wool was then inserted, and the tube was subsequently evacuated and sealed without exposing the Ca metal to air. The ampule was heated to 550ºC, kept at that temperature for 8 hours, and then slowly cooled (3ºC per hour) to 310ºC at which temperature the excess Bi was spun off with the aid of a centrifuge (3000 rpm, Heat capacity and electrical resistivity measurements were performed using a 3 He-refrigerator equipped Quantum Design PPMS system. Electrical contacts were glued to the sample surface using silver paste. A standard relaxation method was used for the heat capacity measurements.Magnetic susceptibility measurements were carried out in a Quantum Design MPMS-XL SQUID magnetometer equipped with an iQuantum 3 He refrigerator.Electronic band structure calculations were performed using the plane-wave pseudopotential III ResultsThe EDS results yielded the Ca:Bi ratio of 1:2, confirming the stoichiometry of the grown crystals. Additionally, some elemental Bi spots on the surface were found. They may originate either from remaining flux material that was not removed during the centrifugation process, or arise from CaBi 2 decomposition in contact with air and moisture. The room temperature PXRD pattern of crushed crystals is presented in Fig. 2 (the increased background in the low 2θ range is due...

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Type-I superconductivity in KBi₂single crystals

Cited by 35 publications

References 26 publications

Narrow-gap semiconducting properties of KMgBi with multiband feature

Narrow-gap semiconducting properties of KMgBi with multiband feature

Electronic band structure and superconducting properties of SnAs

Superconductivity in CaBi₂

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Type-I superconductivity in KBi2single crystals

Cited by 35 publications

References 26 publications

Narrow-gap semiconducting properties of KMgBi with multiband feature

Narrow-gap semiconducting properties of KMgBi with multiband feature

Electronic band structure and superconducting properties of SnAs

Superconductivity in CaBi2

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Type-I superconductivity in KBi₂single crystals

Superconductivity in CaBi₂